m21117 Recognising and describing angles 1.1 2009/03/28 07:32:52.078 GMT-5 2009/03/28 08:16:44.669 GMT-5 Helen Saayman Helen Saayman mark.horner@shuttleworthfoundation.org Helen Saayman Helen Saayman mark.horner@shuttleworthfoundation.org Helen Saayman Helen Saayman mark.horner@shuttleworthfoundation.org Mathematics and Statistics en

Do you remember what the word parallel means? Write down the definition for it: Invariable 1. A: Yes B: Yes 2. C 1. 1.1 Obtuse 1.2 Right angle 1.3 Rotation 1.4 Acute BRAIN-TEASER! 1. Acute Obtuse Straight Right angle 2. Class discussion:

Do you remember what the word parallel means? Write down the definition for it: _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ Let's begin with some "puzzles"! Look at the sketches below and answer the questions that follow:

1. Indicate whether EF and GH are parallel to one another in figure A: __________________________________________________________________ B: __________________________________________________________________ 2. Which is the extension of F: C or K?

Do you still remember? indicates a line: AB indicates a line segment: EF indicates a radius: CD Two lines that intersect form an angle.

The point where the lines meet is called the vertex. We write this as: ÐABC Did you know? The unit that we use for measuring angles is a degree. We measure the size of the angle in degrees. We write an angle of 60 degrees as 60°. You have to learn the different types of angles: Types of angles 1. The size of a rotation or full turn is 360° 2. A straight angle is a half turn and it is 180°. 3. A right angle is a quarter turn and it is 90°. 4. An acute angle is larger that 0°, but smaller than 90°. 5. An obtuse angle is larger than 90°, but smaller than 180°.

1. How well do you know angles? Work with a partner to see if the two of you can tell what the following angles are: 1.1 _________________________________ 1.2 _________________________________ 1.3 _________________________________ 1.4 _________________________________

Learning Outcome 4:The learner will be able to use appropriate measuring units, instruments and formulae in a variety of contexts. Assessment Standard 4.11: We know this when the learner recognises and describes angles in two-dimensional shapes, three-dimensional objects and the environment.